Biotransformation and Mineralization of BTEX Compounds and MTBE in Waste Mixtures by Enriched and Pure CulturesEPA Grant Number: U914983
Title: Biotransformation and Mineralization of BTEX Compounds and MTBE in Waste Mixtures by Enriched and Pure Cultures
Investigators: Deeb, Rula A.
Institution: University of California - Berkeley
EPA Project Officer: Carleton, James N
Project Period: January 1, 1996 through January 1, 1999
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Fellowship - Environmental Engineering , Academic Fellowships , Engineering and Environmental Chemistry
The objectives of this research project are to: (1) evaluate the biotransformation potentials of benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene (BTEX), and methyl-tert butyl ether (MTBE) in pollutant mixtures; and (2) characterize any potential cosubstrate interactions that may inhibit the mineralization of these compounds in mixtures.
A mixed culture was derived from a gasoline contaminated aquifer and enriched on toluene. Two Rhodococcus species, RR1 and RR2, were isolated from this consortium. All three cultures were shown to degrade each of the BTEX compounds, individually and in mixtures, at a broad range of hydrocarbon concentrations (up to 80 mg/L). The mineralization of each of the BTEX compounds was investigated using 14C-labeled BTEX. The mixed culture mineralized each of the six BTEX components, individually and in mixtures. Although the two pure isolates biotransformed each of the parent BTEX components, both of these cultures were unable to mineralize o-xylene. Studies were performed to elucidate the biochemical pathways employed by RR1 and RR2 in mineralizing BTE(m-/p-)X mixtures. These studies revealed that BTEX compounds were being degraded via a TOD-like pathway. Studies to evaluate substrate interactions caused by the concurrent presence of multiple BTEX compounds revealed a range of substrate interaction patterns including no interaction, stimulation, competitive inhibition, noncompetitive inhibition, and cometabolism.